Electrical induction apparatus



Aug. 24,

L. c. WHITMAN 2,447,883 mcrkrcu xunucnon Arrnnus Filed larch 30, 194.4

In'ventor': Lawrence C. Whitman,

His Attorney- Patented Aug. 24, 1948 2,447,883 ELECTRICAL INDUCTIONAPPARATUS Lawrence C. Whitman, Pittsiield, Mass assignor to GeneralElectric Company, a corporation of New York Application March so, 1944,Serial No. 528,716

1 9 Claims.

My invention relates to electrical induction ap- Daratus such astransformers and reactors and to the type in which the 'core and coilsare immersed in an insulating and cooling dielectric liquid.

In the manufacture of electrical induction apparatus, such astransformers which'have a liquid filled casing, it is customary toemploy a gas chamber or conservator on the top of the transformer casingwhich communicates with the inside of the transformer casing. In someapplications, however, where the height of the apparatus should be keptto a minimum it has been suggested to place the gas expansion chamberother than on top of the casing, such as on the side thereof. Suchliquid filled apparatus has also been cooled by the use of .coolingradiators which are connected to the top and bottom of the casing sothat the dielectric fluid may circulate by free convection up throughthe core and coils and down through the radiator.

It is therefore an object of my invention to provide a liquid filledelectric induction apparatus with an improved expansion chamberconstruction.

A further object of my invention is to provide an electric inductionapparatus of the liquid filled type which has a minimum height and floorspace.

A further object of my invention is to reduce the quantity of liquidnecessary for filling the casing of a liquid filled electric inductionapparatus.

A still further object of my invention is to provide an improvedarrangement for cooling an electric induction apparatus.

Further objects and advantages of my invention will become apparent fromthe following description referring to the accompanying drawing, and thefeatures of novelty which characterize my invention will be pointed outwith particularity in the claims annexed to and forming a part of thisspecification.

In the drawing, Fig. 1 is a side elevationin partial section of atransformer which is provided with an embodiment of my invention; Fig. 2is an end view in section of the transformer illustrated in Fig. 1.

In the construction illustrated in the drawing I have shown my inventionas applied to an electrical induction apparatus, such as a transformer,but it will be understood that my invention may be employed with anyother suitable type of electrical apparatus which is liquid filled. Theconstruction as shown in the drawing includes any suitable type of core[0 with cells H surrounding the core winding leg. Enclosing the core andcoils is a casing II. A cover I: is pr0- vided so that the casing andcover provide a substantially fluid tight enclosing casing. Suitablebushings H are placed in the casing side walls for lead-in conductorswhich connect to the coils i I. It will be understood that any suitablebushing may be employed which is substantially fluid tight and has atight seal with the casing. In order to provide a cooling and dielectricliquid for the core and coils the casing contains any suitable liquidsuch as oil or a chlorinated hydrocarbon of the type described in Patent1,931,373 to Clark, issued October 17, 1933, and assigned to the sameassignee as this present invention.

In' order to provide a suitable expansion chamber for absorbing thepressure changes due to expansion of the liquid during increases intemperature, I provide an expansion chamber it which is insidethe-casing 82, such as being near the top thereof. The expansion chamberincludes partitions ii and I! and a bottom 18, the partitions II and Hbeing attached to the lower surface of the cover I 3 in anysuitablemanner such as by welding to provide a substantially fluid tightjoint. The expansion chamber H5 may be filled with a suitable gas suchas nitrogen. Communication is provided between the gas expansion chamberand the inside of the casing by an opening 19 in the side wall ll of thegas expansion chamber.

In order to allow for a suitable expansion of the liquid, the liquid isfilled to a level which at no load will be below the top of thetransformer casing and preferably in the vicinity of the bottom 18 ofthe gas expansion chamber such as at a level indicated by the line 20.Furthermore,

the side walls 96 and I! of the gas expansion chamber are spaced fromside walls 2| and 22 respectively of the casing a predetermined amountwhich depends upon the size of the casing and the amount of liquidemployed so.

that upon heating of the liquid, the liquid will rise into the spacebetween the side walls of the gas expansion chamber and the casing.Thus,

Y when the liquid is heated due to any predetermined load on thetransformer, such for example full load, the oil may rise in the spacebetween the side walls am; suitable amount such as that indicated by thedash line 24. In order to maintain the liquid at suitable limits oftemperature and pressure, when a predetermined load is reached such asfull load, I provide cooler means which may be of any suitable type andwhich, in the construction illustrated in the drawing, includes aplurality of tubes 25 which are connected at the bottom through a header2| and at the top through a header 21. It will be noted that the header2! communicates with the side wall of the casing at approximately thelevel of the liquid indicated for full load and thus when the levelreaches the header 2'' the oil may circulate by free convection upthrough load or full load condition, a tube 213 is provided which hasone end in the opening it) and the second end 29 adjacent the lowerportion or bottom i! of the gas expansion chamber. Thus the oil uponbeing sumciently heated may. expand into the tube and from there intothe gas expansion chamber. It will also be seen that upon cooling of theoil such as will happen when the load is removed, the oil will begin tocontract and due to the siphon tube 28 the oil will not be left in thebottom of the gas expansion chamber but due to the pressure built up bydisplacing the gas in the gas expansion chamber, the compressed gas willforce any oil above the bottom 29 through the tube and into the maincasing. It will be understood, of course, that there may be a very smallvolume of liquid left in the bottom of the gas expansion chamber in thespace between the bottom of. the siphon tube 28 and the bottom it of thegas expansion chamber. However, this may be made a minimum amount withinthe usual manufacturing tolerances.

It will be seen from the above that I have provided a casing and gasexpansion chamber construction for an electric apparatus such as atransi'ormer which has a minimum of height and weight, since theexpansion chamber is placed inside the tank which will also use aminimum of liquid since the volume of the gas expansion chamber willdisplace the amount of liquid which overwlse would be used were theexpansion chamber placed outside the tank. In order that the liquid mayexpand in the space between the side walls of the gas expansion chamberand the casing, the proportions of the sides of the casing and gasexpansion chamber may be made any suitable value. Thus for example inthe drawing, if the total height of the transformer is about 56 inches,

the gas expansion chamber may be about inches high and with a spaceabout 1 inch between the side walls of the gas expansion chambet and theadjacent side walls of the casing. Thus with the oil having a level atnoload or at degrees C. approximately in line with the bottom id of thegas expansion chamber, upon full load the oil will reach a level atabout 2 inches below the top of the casing, and by providing the header2'! of the cooler tube at slightly below this level the liquid willcirculate through the cooler tube upon reaching approximately full load.Furthermore, the opening it may be placed any suitable place, such asslightly above the full load level or for a transformer having thedimensions as given above of approximately between an inch and a halfinch from the top of the casing.

For protecting the apparatus against sudden internal pressure increaseswhich might result from a. short circuit or heavy overload I provide arupturable diaphragm supported in an opening in the bottom wall it ofthe gas expansion chamber, as illustrated in Fig. 2. The diaphragm maybe supported relatively tightly over the opening in any suitable 'mannersuch as by the use of a collar 3 I Any suitable means may be employedmenses for rupturing th diaphragm upon the attainment of a predeterminedpressure in the transformer casing, such as by a. diaphragm rupturingarrangement 32 which is described in further detail in Patent 2,337,361to Vienneau, issued December 31, 1943, and assigned to the same assigneeas this present invention. By providing the rupturable diaphragm in thewall of the expansion chamber instead of in the outer wall of thtransformer casing, high pressures due to a fault in the transformerwhich are not equalized through the relatively small tube 28 may bequickly released into the chamber it without exposing the insulatingoutside air. Also any small quantities of smoke or fumes released by theliquid due to the fault,

will not contaminate the outside air, which may be an importantconsideration when the transformer is installed in an enclosed room.such as in a basement.

Although I have shown and described particular embodiments of myinvention, I do not desire to be limited to the particular embodimentsdescribed. and I intend in the appended claims to cover allmodifications which do not depart from the spirit and scope of myinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An electric induction apparatus including an enclosing casing,partition means providing a chamber within said casing and in thevicinity of the top of said casing, said partition means providing sidewalls of said chamber spaced from the side walls of said casing, adielectric liquid within said casing and having a no load level belowthe top of said casing so that upon heating 'said liquid may expand intothe space between the side walls of said chamber and said casing, gas insaid chamber, means providing an opening between said casing and chamberin the vicinity of the full load level of said liquid, and means forreturning said liquid from said chamber to said casing when the liquidlevel in the casing falls below said full load level after rising aboveit.

2. An electric induction apparatus including an enclosing casing,partition means providing a chamber within said casing and in thevicinity of the top of said casing, said partition means providing sidewalls of said chamber spaced from the side walls of said casing. adielectric liquid within said casing and having a no load level belowthe top of said casing so that upon heating said liquid may expand intothe space between the side walls of said chamber and said casing, gas insaid chamben-and tube means having an end in an opening in a side wallof said chamber in the vicinity of the full load level of said liquidand another end within said chamber near the bottom thereof.

3. An electric induction apparatus including an enclosing casing,partition means providing a chamber within said casing and in thevicinity of the top of said casing, said partition means pro- Vidingside walls of said chamber spaced from the side walls of said casing, anopening in the side walls of said chamber near the top thereof, adielectric liquid within said casing and having a no load level near thebottom of said chamber so that upon heating said liquid may expand intothe space between the side walls of said chamber and said casing, gas insaid chamber, cooler means having connection with said casing near thebottom thereof and near the top thereof below the level of said liquidat a predetermined load so I Q I A V that liquid may circulate in saidcasing and cooler upon said apparatus reaching said predetermined load.

4. An electric induction apparatus including an enclosing casing,partition means providing a chamber within said casing, a dielectricliquid in said casing having a no load level near the bottom of saidchamber, said partition means providing a side wall of said chamberspaced from a side wall of said casing a predetermined amount inrelation to the amount of liquid and size of the casing so that uponheating said liquid will expand into the space between said spaced sidewalls of said chamber and casing to a predetermined level upon saidapparatus reaching a predetermined load, an opening in th side wall ofsaid chamber near the top thereof, and cooler means connected to saidcasing in the vicinity of said predetermined level of said liquid sothat said liquid may flow into said cooler and be cooled.

5. An electric induction apparatus including an enclosing casing,partition means providing a chamber within said casing, a dielectricliquid in said casing having a no load level below the top of saidcasing, said partition means providing a side wall of said chamberspaced from a side wall of said casing a predetermined amount inrelation to the amount of liquid and size of the casing so that uponheating said liquid will expand into the space between said spaced sidewalls of said chamber and casing to a predetermined level upon saidapparatus reaching a predetermined load, and a tube in an opening insaid side wall of said chamber in the vicinity of said predeterminedload and another end near the bottom of said chamber.

6. An electric induction apparatus including an enclosing casing,partition means providing a chamber within said casing, a dielectricliquid in said casing having a no load level below the top of saidcasing, said partition means providing a side wall of said chamberspaced from a side wall of said casing a predetermined amount inrelation to th amount of liquid and size of the casing so that uponheating said liquid will expand into the space between said spaced sidewalls of said chamber and casing to a predetermined level upon saidapparatus reaching a predetermined load, cooler means connected to saidcasing in the vicinity of said predetermined level of said liquid sothat said liquid may flow into said cooler and be cooled, and a tube inan opening in said side wall of said chamber above said predeterminedlevel with an end inside said chamber near the bottom thereof.

7. In combination, an nclosing casing for electric apparatus, a hollowchamber attached to the inner side of the cover of said casing andextending down into said casing, a liquid filling said casing tosubstantially the level of the bottom of said chamber when saidapparatus is unloaded, an opening in said chamber near the top thereof,a gas filling said chamber and the space in said casing above the levelof said liquid, and an external radiator connected to said casing nearthe bottom thereof and near the top thereof below the level of saidopening in said chamber, the volume between the walls of said casing andchamber being such that the full load heating of said apparatus expandssaid liquid until it rises between said walls to a level which isbetween said opening in said chamber and the upper connection of saidradiator to said casing.

8; In combination, an enclosing casing for electrical apparatus, ahollow chamber attached to the inner side of the cover of said casing,and extending down into said casing with an annular space between thewalls of said chamber and casing,-a liquid filling said casing tosubstantially the level of the bottom of said chamber when saidapparatus is unloaded, an opening in said chamber,near the top thereof,a gas filling said chamber and the space in said casing above the levelof said liquid, an external radiator connected to said casing near thebottom thereof and near the top thereof below the opening in saidchamber, the volume between the walls of said casing and chamber beingsuch that full load heating of said apparatus expands said liquid untilit rises between said walls to a level which is between said opening insaid chamber and the upper connection of said radiator to said casing,and a pipe connected to said opening in said chamber and extendingdownwardly into said chamber substantially to the bottom thereof wherebyany of said liquid which is forced into said chamber as a result ofoverloading of said apparatus will be returned to said casing throughsaid pipe by the pressure of the gas in said chamber during subsequentcooling of said liquid.

9. In combination, an enclosing casing for electrical apparatus, ahollow chamber attached to I the inner side of the cover of said casingand extending down into said casing with an annular space between thewalls of said chamber and casing, a liquid filling said casing tosubstantially the level of the bottom of said chamber when saidapparatus is unloaded, an opening in said chamber near the top thereof,a gas filling said chamber and the space in said casing above the levelof said liquid, an external radiator connected to said casing near thebottom thereof and .near the top thereof below the opening in saidchamber, the volume between the walls of said casing and chamber beingsuch that full load heating of said apparatus expands said liquid untilit rises between said walls to a level which is between said opening insaid chamber and the upper conassurances crrnn The following referencesare of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,232,834 Nichols July 10, 191!1,721,331 Bugatti July 18, 1929 2,337,361 Vienneau Dec. 21, 1943 FOREIGNPATENTS Number I Country Date 158,698 Germany Feb. 25, 1905 527,486

Germany June 18, 1931

